If the rain clouds part, you can see a blue moon and the planet Mars at its brightest this weekend.
The full moon arrives at 5:14 p.m. Saturday, though it won't rise until 8:07 p.m. in Baltimore. Typically, May's full moon is known as the Flower Moon, Corn Planting Moon or Milk Moon, according to the Farmer's Almanac.
It is also a blue moon because it is the third of four full moons to occur this spring. Most seasons have just three full moons. The first this spring occurred just after the vernal equinox March 23, and the last occurs hours before the summer solstice on June 20.
That doesn't mean it will appear blue, or that it will be any bigger or brighter than it otherwise would.
It will have a bright companion, though. Mars will be at its brightest since 2003 because it will be unusually close to Earth at the same time it reaches what is known as opposition, when its face is fully illuminated by the sun.
The last time such a coincidence occurred was Aug. 28, 2003, and the next isn't until July 27, 2018, according to EarthSky.org.
Unfortunately, it could be difficult to spot both. If the clouds part Saturday night, with rain expected through the evening, you can spot the moon and Mars side by side moving across the southern half of the sky.
Mostly cloudy skies are also forecast Sunday evening, though they are expected to clear through the night. On Sunday night, Saturn will be the bright planet right next to the moon, with bright Mars a little farther away.